Controls for air collers and dehumidifiers



Nov. 3, 1964 w. K. KYLE CONTROLS FOR AIR CooLERs AND DEHUMIDIFIERS Filed March 26, 1962 United States Patent O 3,155,156 CONTROLS FR AIR CGOLERS AND DEHUMIDIFERS William K. Kyle, Staunton, Va., assigner to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Filed Mar. 26, 1962, Ser. No. 182,538 3 Claims. (Cl. 165-21) This invention relates to air conditioning units, and relates more particularly to controls for the operation of such units as air coolers, and as air dehumidiiiers.

In a typical control circuit for operating an air conditioning unit as an air cooler or as an air dehumidifier, a thermostat is used to start the refrigerant compressor of the unit when air cooling is required, and a humidistat is used to start the compressor for reducing the temperature of the air to its dew point, and to turn on an electric heater for raising the sensible heat of the dehumidied air to that required for comfort, when dehumidiiication is required. In prior control circuits of this type, when the thermostats were satisiied, they-turned 01T the compressors when the humidistats were calling for dehumidication, requiring restarting of the compressors by the humidistats.

An object of this invention is to operate the refrigerant compressor of an air conditioning unit continuously under control of a thermostat and a humidistat when either cooling or dehumiditication is required.

This invention will now be described with reference to the annexed drawing which is a diagrammatic view of one embodiment of this invention.

Referring now to the drawing, a fan F driven by a fan motor FM is arranged to blow air over an evaporator coil 12 and an electric heater EH. The coil 12 is connected by a capillary tube 14 to the outlet side of a condenser coil 16, the inlet side of which is connected by a tube 17 to the discharge side of a refrigerant compressor C driven by an electric motor CM. The suction side of the compressor C is connected by a tube 20 to the outlet side of the evaporator coil 12.

The fan motor FM is connected electrically across the compressor motor CM. The latter is connected by a wire 19 to an electric supply line L1, and by a wire 21 to switch MSS of starter relay MS. The latter is connected by a wire 23 to electric supply line L2. The relay MS has an energizing coil 24, one end of which is connected by Wire 25 to Wire 19 and through the latter to the supply line L1, and the other end of which is connected by wire 26 to armature 27 which forms with one contact of control relay CR, a switch CRS1 shown by the drawings as closed, and which forms with another contact of the relay CR, a switch CRSZ shown by the drawings as open. The switch CRS1 is connected by Wire 31 to one end of winding Sti of reheat relay RR, the other end of which is connected by Wire 32 to the wire 25 and through the latter and the wire 19 to the supply line L1. The reheat relay RR has a switch RRS with two contacts, one of which is connected by wire 34 to the wire 23 and through the latter to the supply line L2, and the other of which is connected by wire 35 to one end of the heater EH, the other end of which is connected to the supply line L1.

A room thermostat T has a switch TS connected to the supply line L2 and to one end of energizing winding 41 of the control relay CR, the other end of which is connected by wire 43 to the wire 19 and through the latter to the supply line L1. The switch CRS2 of the relay CR is connected by wire 47 to the supply line L2.

A room humidistat H has a switch HS connected across the switch CRS2 of the control relay CR.

The drawing shows the thermostat T as satisiied, with its switch TS open, and shows the humidistat H as calling for dehumidicaticn, with its switch HS closed. As a relCe sult of the switch TS being open, the control relay CR is deenergized, with its switch CRS1 closed, and its switch CRS2 open. The closed switch HS has connected the starter MS to the supply lines, energizing the starter which has closed its switch MSS connecting the compressor motor CM and the fan motor FM to the supply lines L1 and L2. The closed switches HS and CRS1 have connected the reheat relay RR to the supply lines L1 and L2, energizing the relay RR which has closed its switch RRS connecting the heater EH to the supply lines L1 and L2. The compressor C is operated to supply, through the condenser 16 and the capillary tube 14 which acts as an expansion device, refrigerant to the evaporator coil 12 to chill the air blown over it by the fan F, lowering its temperature to its dew point so that moisture is condensed from it. The heater EH increases the sensible heat of the chilled air to that required for comfort.

If the thermostat T calls for cooling and closes its switch TS while the humidistat H is calling for dehumiditication, it turns off the heater EH by connecting the control relay CR to the supply lines L1 and L2, energizing the relay CR which opens its switch CRS1 and closes its switch CRS2. The opening of the switch CRS1 deenergizes the relay RR which opens its switch RRS and deenergizes the heater EH. The now closed switch CRS2 is connected across the humidistat switch HS and if the latter opens while the thermostat is calling for cooling, the operation of the compressor C and the fan F is continued since the starter MS is energized through the closed switch CRSZ.

If the system has been operating under control of the thermostat T with the humidistat satisfied, when the latter calls for dehumidication and closes it switch HS, nothing else can happen until the thermostat is satised, for it takes priority over the humidistat. When the thermostat is satislied, it opens its switch TS to deenergize the control relay CR, and the latter then opens its switch CRSZ placing the humidistat switch HS in control of the starter relay MS and through the switch MSS of the latter, in control of the compressor and fan motors, and closes its switch CRS1, placing the humidistat switch HS in control of the reheater relay RR, and through the switch RRS of the latter, in control of the heater EH.

During the transfer of control from the humidistat to the thermostat and vice versa, the compressor and fan operate continuously if either the humidistat or the thermostat is not satisfied. This results in smoother operation of the system, and in reduced Wear of the compressor and fan motors and of the starter relay MS.

What is claimed, is:

1. ln an air conditioning system having a refrigerant compressor connected to an air chilling evaporator, having an electric motor for driving said compressor, having an electric heater for heating the air chilled by said evaporator, and having electric supply connections, the combination of a control relay, a thermostat having a switch which closes when the temperature of the air rises to a predetermined value, means including said switch for connecting said relay to said connections, said relay having a first switch which is opened and having a second switch which closes When said relay is energized by the closing of said switch of said thermostat, means including said first switch for connecting said heater to said connections, means including said second switch for connecting said motor to said connections, and a humidistat having a switch which closes when the humidity of the air rises to a predetermined value, connected across said second switch.

2. In an air conditioning system having a refrigerant compressor connected to an air chilling evaporator, having an electric motor for driving said compressor, having an electric heater for heating the air chilled by said evaporator, and having electric supply connections, the combination of a control relay having a irst switch which is opened and having a second switch which closes when said relay is energized, a thermostat having a switch which closes when the temperature of the air rises to a predetermined value, means including said thermostat switch for connecting said relay to said connections, a reheat relay having a switch which is closed when said reheat relay is energized, means including said switch of said reheat relay for connecting said heater to said connections When said reheat relay is energized, means including said rst switch for connecting said reheat relay to said connections, a starter relay having a switch which is closed when said starter relay is energized, means including said switch of said starter relay for connecting said motor to said connections when said starter rellay is energized, means including said second switch for connecting said starter relay to said connections, and a humidistat having a switch which closes when the humidity of the air rises to a predetermined value, connected across said second switch.

3. In an air conditioning system having a refrigerant icompressor connected to an air chilling evaporator, having an electric motor for driving said compressor, having a heater for heating the air chilled by said evaporator, and having electric supply connections, the combination of a control relay having a rst switch which is opened and having a second switch which closes when said relay is energized, means including one of said switches for energizing said heater, means including the other of said switches for connecting said motor to said connections, a humidistat having a switch which closes when the humidity of the air rises to a predetermined value, connected across said other switch, a thermostat having a switch which closes when the temperature of the air rises to a predetermined value, and means including said thermostat switch for connecting said relay to said connections.

References Cited in the file of this patent UNITED STATES PATENTS 

1. IN AN AIR CONDITIONING SYSTEM HAVING A REFRIGERANT COMPRESSOR CONNECTED TO AN AIR CHILLING EVAPORATOR, HAVING AN ELECTRIC MOTOR FOR DRIVING SAID COMPRESSOR, HAVING AN ELECTRIC HEATER FOR HEATING THE AIR CHILLED BY SAID EVAPORATOR, AND HAVING ELECTRIC SUPPLY CONNECTIONS, THE COMBINATION OF A CONTROL RELAY, A THERMOSTAT HAVING A SWITCH WHICH CLOSES WHEN THE TEMPERATURE OF THE AIR RISES TO A PREDETERMINED VALUE, MEANS INCLUDING SAID SWITCH FOR CONNECTING SAID RELAY TO SAID CONNECTIONS, SAID RELAY HAVING A FIRST SWITCH WHICH IS OPENED AND HAVING A SECOND SWITCH WHICH CLOSES WHEN SAID RELAY IS ENERGIZED BY THE CLOSING OF SAID SWITCH OF SAID THERMOSTAT, MEANS INCLUDING SAID FIRST SWITCH FOR CONNECTING SAID HEATER TO SAID CONNECTIONS, MEANS INCLUDING SAID SECOND SWITCH FOR CONNECTING SAID MOTOR TO SAID CONNECTIONS, AND A HUMIDISTAT HAV- 